Controlled leakage centrifugal pump

ABSTRACT

The cost of a centrifugal pump is reduced by providing it with a generally cylindrical casing having a radial discharge nozzle near the upper end of the casing and a suction nozzle at the lower end. The casing is bolted to a main flange having a cylindrical neck extending downwardly inside the casing. The pump shaft extends through the neck and the main flange. A radial bearing assembly is bolted to the lower end of the neck. In certain applications, breakdown bushings surround the shaft within the neck and controlled leakage shaft seals are disposed in the main flange, thereby confining the high pressure liquid within the casing and the main flange. A cooler surrounds the shaft between the pump impeller and the radial bearing assembly. A thermal barrier surrounds the bearing assembly.

O Umted States Patent 1151 3,652,179 Hagen 1 Mar. 28, 1972 [54] CONTROLLED LEAKAGE 2,994,004 7/1961 Macha et a1. ..103;310/111;42 CENTRIFUGAL PUMP 3,017,072 1/1962 Hagg et a1... ..415/170 879,484 2/1908 Morterud..... ...415/111 1 lnvemofl 1 8*" Greensburs, 2,257,011 9/1941 Hillier ...415/175 73 Assi nee: w u Imuse Electric Cor ration 2,330,730 9/1943 Mosshart ...415/1 1 1 I 1 g sburghfpa' 1 2,864,314 12/1958 Culleton .415/111 3,459,430 8/1969 Ball 415/112 il M r- 1 1971 3,554,661 1/1971 Oglesby et a1. 415/112 [211 App, 123039 Primary Examiner-Henry F. Raduazo Related US. Application Data y- Smmo" [63] Continuation of Ser. No. 810,312, Mar. 25, 1969, 57 S R abandoned.

The cost of a centr1fuga1 pump is reduced by providing it with 52 us. 01 ..415/111, 415/170, 415/175, generally cylindrical casing'having a radial discharge 415/215 308/77 415/112 near the upper end of the casing and a suction nozzle at the 51 1m. (:1. ..110211 15/00, F04d 29/00 F166 1/24 1Wer The casing is blted a main flange having a cylin- [58] Field Of Search ..415/111 112 175 170- drical neck extending downwardly inside casing- The g 3 i pump shaft extends through the neck and the main flange. A g radial bearing assembly is bolted to the lower end of the neck. In certain a lications breakdown bushin s surround the 1 PP E [56] References C ted shaft within the neck and controlled leakage shaft seals are UNITED STATES T S disposed-in the main flange, thereby confining the high pressure liquid within the casing and the main flange. A cooler sur- 2,239,228 4/1941 Hanklson ..103/103 rounds thevshaft between the pump impeller and h di 2,381,777 8/1945 bearing assembly. A thermal barrier surrounds the bearing as- 2,483,335 9/1949 embly. 2,799,227 7/1957 2,885,963 5/1959 23 Claims, 4 Drawing Figures PATENTEDmzs 1972 3,652,179

sum 1 OF 2 FIG .I.

INVENTOR Oskc|r Ha gen TQRNEY BY q 4i PATENTED MAR 2 8 1972 SHEET 2 [1F 2 FIG.3.

CONTROLLED LEAKAGE CENTRIFUGAL PUMP This application is a continuation of application Ser. No. 810,312, filed Mar. 25, 1969; now abandoned.

BACKGROUND OF THE INVENTION This invention relates generally, to hydraulic pumps and, more particularly, to centrifugal pumps of the controlled leakage shaft seal type.

Prior pumps of the above-identified type have had a casing of a bowl type with a cooler, radial bearing assembly, breakdown bushings and shaft seals all mounted above the main flange area of the pump structure, thereby requiring an expensive casing and a relatively long pump structure.

An object of this invention is to reduce the height and the cost of manufacturing a centrifugal pump suitable for handling high pressure temperature liquids.

Another object of the invention is to improve the effectiveness of a thermal barrier mounted within the casing of a centrifugal pump.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

' SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, a centrifugal pump is provided with a generally cylindrical casing having a radial discharge nozzle near the upper end of the easing and a suction nozzle at the lower end of the casing. The upper end of the casing is bolted to a main flange having a generally cylindrical neck extending downwardly insideth e casing. The pump shaft extends through the neck and the main flange. A cooler, radial bearing assembly, breakdown bushings and thermal barrier are all disposed within the cylindrical casing. Controlled leakage shaft seals are disposed in the mainflange, thereby confining the high pressure liquid within the.

casing and the main flange. The effectiveness of the thermal barrier is increased by providing a plurality of spaced concentric sleeves within the barrier which contains liquid from the pump casing.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, particularly to FIG. 1, the centrifugal pump shown therein comprises a generally cylindrical casing 11 having a radial discharge nozzle 12 near the upper end of the casing and a suction nozzle 13 at the lower end of the casing, a main annular flange 14 having a generally cylindrical neck 15 extending downwardly inside the casing 11, a shaft 16 extending through the flange l4 and the neck 15, and an impeller 17 attached to the lower end of the shaft 16 by means of an impeller nut 18 and a bolt 19. The shaft 16 may be driven by an electric motor (not shown) mounted on a motor support stand 21 attached to the top of the main flange 14 by bolts 22. The shaft of the motor is connected to the shaft 16 by means of a coupling 23. The upper end of the casing 11 is attached to the main flange 14 by means of bolts 24 which extend through the flange 14 and are threaded into the casing 1 1.

Referring to FIGS. 3 and 4, it will be seen that the casing 11 is of a relatively simple configuration. The casing may be made from high strength carbon steel and, if desired, the inside of the casing may be provided with a lining or cladding composed of a corrosion resistant material, such as Inconel. In view of the cylindrical shape of the casing, the material may be utilized to the fullest extent of the allowable stresses.

As shown in FIG. 1, a radial bearing assembly 25 for the shaft 16 is attached to the lower end of the neck 15 by means of bolts 26. The bearing assembly 25 may be of any suitable type. As shown, the assembly includes a sleeve 27 pressed on the shaft 16, suitable bearing material 28 and a housing 29 enclosing the bearing material 28.

As also shown in FIG. 1, breakdown bushings 31 surround the shaft 16 inside the neck 15 above the bearing assembly 25. The bushings 31 may be of a type well known in the art. Shaft seals of a controlled leakage type are disposed in the main flange 14 above the breakdown bushings. The seals are retained in position by a housing 32 attached to the top of the flange 14 by bolts 33. A vapor seal housing 34 is attached to the seal housing 32 by means of bolts 35. A cover 36 for the housing 34 is attached to the housing by means of bolts 37. The shaft seals within the housings 32 and 34 may be of a type well known in the art, such as, for example, the seal arrangement described in US. Pat. No. 3,347,552, issued Oct. 17, 1967 to Erling Frisch. A suitable leak-off connection may be made to the housing 32 by means of a coupling 38 and a pipe 39 attached to the housing 32. Likewise, a leak-off connection may be made to the housing 34 by means of a coupling 41 and a pipe 42 attached to the housing 34. The leak-off liquid is returned to the circulatory system in a manner well known in the art.

The present pump is suitable for circulating a liquid in a circulatory system at a relatively high temperature and a high pressure. Suitable connectionsmay be made to the suction nozzle 13 and to the discharge nozzle 12 to enable the pump to circulate the liquid in the system.

In addition to the impeller 17, the pump includes a main impeller seal ring 42, a diffuser 43 extending upwardly from the impeller 17 inside the casing 11 and a guide elbow 44 connecting the diffuser 43 with the radial discharge nozzle 12. Thus, the liquid drawn into the pump through the suction nozzle 13 by the impeller 17 is directed to the discharge nozzle 12 by means of the diffuser 43 and the elbow 44.

In order to protect the bearing assembly 25 and the shaft seals in housings 32 and 34 from the heat of the high temperature liquid circulated by the pump, a cylindrical thermal barrier 45 surrounds the bearing assembly '25, and a cooler 46 is disposed between the impeller 17 and the bearing assembly 25. The cylindrical barrier 45 includes an inner wall 47 and an outer wall 48 spaced from the inner wall 47. The upper ends of the walls 47 and 48 are secured to a thermal barrier flange 49, as by welding. The flange 49 is clamped between the main flange 14 and the casing 11 by means of the flange bolts 24. The lower end of the cylinder formed by the inner wall 47 is closed by a bottom wall 51 through which the shaft 16 extends. A labyrinth seal 52 is provided in the wall 51 for the shaft 16. The outer wall 48 extends to a flange 53 on the inner wall 47. The diffuser 43, is attached to the flange 53, as by welding. The guide elbow 44 has upwardly extending support members 54 and 55 which are attached to the flange 49 by means of bolts 56.

Provision is made for circulating a cooling liquid, such as water, through the thermal barrier 45 and the cooler 46. As shown, passageways 57 and 58 in the flange 49 communicate with semi-cylindrical pipes 60 and 70, respectively. These pipes extend through the space between the inner wall 47 and the outer wall 48 of the thermal barrier. The pipe 60 communicates with a chamber 75 through an opening 76 in the flange 53. Likewise, the pipe 70 communicates with a chamber 77 through an opening 78 in the flange 53. The chamber 75 is enclosed by a shield 79 welded to the flange 53 and the bottom wall 51. The chamber 77 is enclosed by a similar shield 81. The chambers 75 and 77 are separated from each other by suitable barriers (not shown).

The passageway 57 may be connected to a suitable supply source by means of a pipe 59. A discharge pipe 61 is connected to the passageway 58.

As shown, the cooler 46 includes a plurality of coils 65 disposed around the shaft 16 within the inner wall 47 of the thermal barrier 45 and between the bottom wall 51 of the barrier and a cover 66 retained in position by bolts 67 threaded into the bottom wall 51. The coils 65 communicate with the chambers 75 and 77, thereby permitting the cooling liquid to circulate through the coils 65 as it flows from the chamber 75 into the chamber 77 from which it is discharged through the pipes 70 and 61. Some of the liquid being circulated by the main impeller 17 is admitted from the pump casing l 1 into the thermal barrier 45 through openings 82 in the outer wall 48. Thus, the thermal barrier is filled with liquid which is cooled somewhat by the liquid flowing through the pipes 60 and 70.

In order to increase the effectiveness of the thermal barrier 45, a plurality of concentric spaced sleeves 62 are provided between the inner wall 47 and the outer wall 48. As shown more clearly in FIG. 2, the sleeves 62 may be maintained in spaced relation by means of spacing washers or nuts 63 mounted on bolts 64 which extend through the outer wall 48 and are threaded into the inner wall 47. The sleeves 62 separate the liquid inside the thermal barrier into vertical layers, thereby increasing the effectiveness of the thermal barrier 45.

As shown in FIG. 1, relatively small openings 71 and 72 are provided in the impeller 17 to admit liquid into a chamber 73 above the impeller and a clearance 74 is provided between the cover 66 and the shaft l6.ln=this manner, a relatively small amount of the liquid being circulated by the impeller 17 is permitted to flow through the labyrinth seal 52 and the cooler 46 into the area around the bearing assembly 25. This liquid is cooled by the cooling coils 65. Thus the bearing assembly and the shaft seals are protected from the heat of the liquid being circulated through the pump by the impeller 17.. v

The present pump is so constructed that the high pressure vessel extends only up to the main flange and not above the main flange as was the case in prior pumps in which the breakdown bushings and the shaft seals were located above the main flange. Thus, the amount of material required to withstand the high pressure is reduced. Furthermore, the total height of the pump is reduced by locating the shaft bearing, the cooler, the thermal barrier, the breakdown bushings and the shaft seals within the casing and the main flange. As previously explained, the cylindrical casing is of a relatively simple construction. Therefore, the cost and the size of the pump are reduced as compared with prior pumps of the same general type.

Since numerous changes may be made in the above described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all subject matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A centrifugal pump comprising a generally cylindrical casing open at one end, said casing having a discharge nozzle and a suction nozzle formed therein, a main flange means covering the open end of said casing and means cooperating with said casing and flange means to form an enclosed space, said main flange means having a generally cylindrical neck extending from said flange means into said enclosed space, a rotatable shaft extending through said flange means and said neck, an impeller attached to the inward end of said shaft and positioned generally in the path between said suction nozzle and said discharge nozzle, a shaft bearing assembly fixedly secured to a structural member in said enclosed space and rotatably receiving said shaft, at least one controlled leakage shaft seal disposed in said main flange means adjacent the neck, said seal receiving leakage flowtherethrough from the space between said neck and said shaft, and cooling means disposed in said enclosed space for cooling said last mentioned leakage flow.

2. The centrifugal pump of claim 1 wherein said cooling means generally surrounds said neck.

3. The centrifugal pump of claim 2 wherein said bearing assembly is attached to the neck and wherein said cooling means generally surrounds said bearing assembly.

4. The centrifugal pump of claim 2 wherein said cooling means comprises a cylindrical thermal barrier generally surrounding said neck.

5. The centrifugal pump of claim 2 wherein said cooling means includes a cooler disposed inwardly of the inward end of said neck, and means for circulating liquid through said cooler. I

6. The centrifugal pump defined in claim 1 wherein said cooling means comprises a plurality of spaced sleeves surrounding at least a portion of said cylindrical neck.

7. The centrifugal pump defined in claim 6 including means for substantially isolating the spaces between said sleeves from the remainder of said enclosed space. i

8. The centrifugal pump defined in claim 6 including an annular cooler disposed at the end of said cooling means remote from said main flange means, and means for circulating liquid through said cooler. I

9. The centrifugal pump defined in claim 3 including means for circulating liquid through at least a portion of the cooling means located adjacent the bearing assembly.

10. A centrifugal pump comprisinga generally cylindrical casing-open at one end, said casing having a radial discharge nozzle near the upper end of the casing and a suction nozzle at the lower end of the casing, a main flange covering the open end of and secured to said casing and having a generally cylindrical neck extending downwardly inside thecasing, a shaft extending through the main flange and the neck, an impeller attached to the lower end of the shaft, a shaft bearing assembly attached to the lower end of the neck, at least one controlled leakage shaft seal disposed in the main flange adjacent the neck at a location above the bearing assembly, said seal receiving leakage 'flow therethrough from the space between said neck and said shaft, and cooling means disposed between the inlet of the pump casing and the seal for cooling said last mentioned leakage flow.

11. The centrifugal pump defined in claim 10 wherein said cooling means comprises a plurality of spaced sleeves surrounding at least a portion of said cylindrical neck.

12. The centrifugal pump defined in claim 11 including means for substantially isolating the spaces between said sleeves from the remainder of said pump casing.

13. The centrifugal pump defined in claim 11 including an annular cooler disposed at the end of said cooling means remote from said main flange, and means for circulating liquid through said cooler.

14. The centrifugal pump defined in claim 1 wherein said cooling means comprises a cylindrical thermal barrier surrounding the bearing assembly and said cylindrical neck.

15. The centrifugal pump defined in claim 14 including means for circulating liquid through at least a portion of the thermal barrier located adjacent the bearing assembly.

16. The centrifugal pump defined in claim 14, wherein the barrier includes an outwardly extending flange at its upper end which is clamped between the main flange and casing.

17. The centrifugal pump defined in claim 10, including a diffuser extending generally upwardly from the impeller inside the casing.

18. The centrifugal pump defined in claim 17, including a guide elbow connecting the diffuser with the radial discharge nozzle inside the casing.

19. The centrifugal pump defined in claim 10, including a seal housing attached to the main flange.

20. The centrifugal pump defined in claim 19, including leak-ofi means for the shaft seal attached to said seal housing, and breakdown bushings surrounding the shaft between the seal housing and the bearing assembly.

tending with the space between the inner and outer walls of the barrier, for circulating a liquid through the coil.

23. The centrifugal pump defined in claim 21, including a plurality of spaced concentric sleeves disposed between said walls.

* i I I l 

1. A centrifugal pump comprising a generally cylindrical casing open at one end, said casing having a discharge nozzle and a suction nozzle formed therein, a main flange means covering the open end of said casing and means cooperating with said casing and flange means to form an enclosed space, said main flange means having a generally cylindrical neck extending from said flange means into said enclosed space, a rotatable shaft extending through said flange means and said neck, an impeller attached to the inward end of said shaft and positioned generally in the path between said suction nozzle and said discharge nozzle, a shaft bearing assembly fixedly secured to a structural member in said enclosed space and rotatably receiving said shaft, at least one controlled leakage shaft seal disposed in said main flange means adjacent the neck, said seal receiving leakage flow therethrough from the space between said neck and said shaft, and cooling means disposed in said enclosed space for cooling said last mentioned leakage flow.
 2. The centrifugal pump of claim 1 wherein said cooling means generally surrounds said neck.
 3. The centrifugal pump of claim 2 wherein said bearing assembly is attached to the neck and wherein said cooling means generally surrounds said bearing assembly.
 4. The centrifugal pump of claim 2 wherein said cooling means comprises a cylindrical thermal barrier generally surrounding said neck.
 5. The centrifugal pump of claim 2 wherein said cooling means includes a cooler disposed inwardly of the inward end of said neck, and means for circulating liquid through said cooler.
 6. The centrifugal pump defined in claim 1 wherein said cooling means comprises a plurality of spaced sleeves surrounding at least a portion of said cylindrical neck.
 7. The centrifugal pump defined in claim 6 including means for substantially isolating the spaces between said sleeves from the remainder of said enclosed space.
 8. The centrifugal pump defined in claim 6 including an annular cooler disposed at the end of said cooling means remote from said main flange means, and means for circulating liquid through said cooler.
 9. The centrifugal pump defined in claim 3 including means for circulating liquid through at least a portion of the cooling means located adjacent the bearing assembly.
 10. A centrifugal pump comprising a generally cylindrical casing open at one end, said casing having a radial discharge nozzle near the upper end of the casing and a suction nozzle at the lower end of the casing, a main flange covering the open end of and secured to said casing and having a generally cylindrical neck extending downwardly inside the casing, a shaft extending through the main flange and the neck, an impeller attached to the lower end of the shaft, a shaft bearing assembly attached to the lower end of the neck, at least one controlled leakage shaft seal disposed in the main flange adjacent the neck at a location above the bearing assembly, said seal receiving leakage flow therethrough from the space between said neck and said shaft, and cooling means disposed between the inlet of the pump casing and the seal for cooling said last mentioned leakage flow.
 11. The centrifugal pump defined in claim 10 wherein said cooling means comprises a plurality of spaced sleeves surrounding at least a portion of said cylindrical neck.
 12. The centrifugal pump defined in claim 11 including means for substantially isolating the spaces between said sleeves from the remainder of said pump casing.
 13. The centrifugal pump defined in claim 11 including an annular cooler disposed at the end of said cooling means remote from said main flange, and means for circulating liquid through said cooler.
 14. The centrifugal pump defined in claim 1 wherein said cooling means comprises a cylindrical thermal barrier surrounding the bearing assembly and said cylindrical neck.
 15. The centrifugal pump defined in claim 14 including means for circulating liquid through at least a portion of the thermal barrier located adjacent the bearing assembly.
 16. The centrifugal pump defined in claim 14, wherein the barrier includes an outwardly extending flange at its upper end which is clamped between the main flange and casing.
 17. The centrifugal pump defined in claim 10, including a diffuser extending generally upwardly from the impeller inside the casing.
 18. The centrifugal pump defined in claim 17, including a guide elbow connecting the diffuser with the radial discharge nozzle inside the casing.
 19. The centrifugal pump defined in claim 10, including a seal housing attached to the main flange.
 20. The centrifugal pump defined in claim 19, including leak-off means for the shaft seal attached to said seal housing, and breakdown bushings surrounding the shaft between the seal housing and the bearing assembly.
 21. The centrifugal pump defined in claim 14, wherein the thermal barrier includes an inner wall and an outer wall spaced from the inner wall.
 22. The centrifugal pump defined in claim 21, including at least one cooling coil surrounding the shaft below the bearing assembly, said coil being enclosed within the inner wall of the barrier, and means communicating with the coil and coextending with the space between the inner and outer walls of the barrier, for circulating a liquid through the coil.
 23. The centrifugal pump defined in claim 21, including a plurality of spaced concentric sleeves disposed between said walls. 